There exists a constant search to develop new olefin polymerization catalysts, catalyst activation processes, and methods of making and using catalysts, that will provide enhanced catalytic activities and polymeric materials tailored to specific end uses. Mono-1-olefins (α-olefins), including ethylene, can be polymerized with catalyst compositions employing titanium, zirconium, vanadium, chromium or other metals, impregnated on a variety of support materials, often in the presence of cocatalysts. These catalyst compositions may be useful for both homopolymerization of ethylene, as well as copolymerization of ethylene with comonomers such as propylene, 1-butene, 1-hexene, or other higher α-olefins.
Catalyst systems comprising metallocene compounds have shown promise in tailoring polymer properties. Catalyst systems comprising organochromium compounds can also be used to modify polymer properties. Accordingly, a process employing both metallocene and organochromium catalysts would provide exceptional control over polymer properties during manufacture. However, there is not a single support capable of activating both types of catalysts. Thus, there remain significant challenges in developing catalysts that can provide custom-made polymers with a specific set of desired properties.